/**
 * @file
 * A Backbone View that provides an entity level toolbar.
 */

(function ($, _, Backbone, Drupal, debounce) {

  'use strict';

  Drupal.quickedit.EntityToolbarView = Backbone.View.extend(/** @lends Drupal.quickedit.EntityToolbarView# */{

    /**
     * @type {jQuery}
     */
    _fieldToolbarRoot: null,

    /**
     * @return {object}
     *   A map of events.
     */
    events: function () {
      var map = {
        'click button.action-save': 'onClickSave',
        'click button.action-cancel': 'onClickCancel',
        'mouseenter': 'onMouseenter'
      };
      return map;
    },

    /**
     * @constructs
     *
     * @augments Backbone.View
     *
     * @param {object} options
     *   Options to construct the view.
     * @param {Drupal.quickedit.AppModel} options.appModel
     *   A quickedit `AppModel` to use in the view.
     */
    initialize: function (options) {
      var that = this;
      this.appModel = options.appModel;
      this.$entity = $(this.model.get('el'));

      // Rerender whenever the entity state changes.
      this.listenTo(this.model, 'change:isActive change:isDirty change:state', this.render);
      // Also rerender whenever a different field is highlighted or activated.
      this.listenTo(this.appModel, 'change:highlightedField change:activeField', this.render);
      // Rerender when a field of the entity changes state.
      this.listenTo(this.model.get('fields'), 'change:state', this.fieldStateChange);

      // Reposition the entity toolbar as the viewport and the position within
      // the viewport changes.
      $(window).on('resize.quickedit scroll.quickedit', debounce($.proxy(this.windowChangeHandler, this), 150));

      // Adjust the fence placement within which the entity toolbar may be
      // positioned.
      $(document).on('drupalViewportOffsetChange.quickedit', function (event, offsets) {
        if (that.$fence) {
          that.$fence.css(offsets);
        }
      });

      // Set the entity toolbar DOM element as the el for this view.
      var $toolbar = this.buildToolbarEl();
      this.setElement($toolbar);
      this._fieldToolbarRoot = $toolbar.find('.quickedit-toolbar-field').get(0);

      // Initial render.
      this.render();
    },

    /**
     * @inheritdoc
     *
     * @return {Drupal.quickedit.EntityToolbarView}
     *   The entity toolbar view.
     */
    render: function () {
      if (this.model.get('isActive')) {
        // If the toolbar container doesn't exist, create it.
        var $body = $('body');
        if ($body.children('#quickedit-entity-toolbar').length === 0) {
          $body.append(this.$el);
        }
        // The fence will define a area on the screen that the entity toolbar
        // will be position within.
        if ($body.children('#quickedit-toolbar-fence').length === 0) {
          this.$fence = $(Drupal.theme('quickeditEntityToolbarFence'))
            .css(Drupal.displace())
            .appendTo($body);
        }
        // Adds the entity title to the toolbar.
        this.label();

        // Show the save and cancel buttons.
        this.show('ops');
        // If render is being called and the toolbar is already visible, just
        // reposition it.
        this.position();
      }

      // The save button text and state varies with the state of the entity
      // model.
      var $button = this.$el.find('.quickedit-button.action-save');
      var isDirty = this.model.get('isDirty');
      // Adjust the save button according to the state of the model.
      switch (this.model.get('state')) {
        // Quick editing is active, but no field is being edited.
        case 'opened':
          // The saving throbber is not managed by AJAX system. The
          // EntityToolbarView manages this visual element.
          $button
            .removeClass('action-saving icon-throbber icon-end')
            .text(Drupal.t('Save'))
            .removeAttr('disabled')
            .attr('aria-hidden', !isDirty);
          break;

        // The changes to the fields of the entity are being committed.
        case 'committing':
          $button
            .addClass('action-saving icon-throbber icon-end')
            .text(Drupal.t('Saving'))
            .attr('disabled', 'disabled');
          break;

        default:
          $button.attr('aria-hidden', true);
          break;
      }

      return this;
    },

    /**
     * @inheritdoc
     */
    remove: function () {
      // Remove additional DOM elements controlled by this View.
      this.$fence.remove();

      // Stop listening to additional events.
      $(window).off('resize.quickedit scroll.quickedit');
      $(document).off('drupalViewportOffsetChange.quickedit');

      Backbone.View.prototype.remove.call(this);
    },

    /**
     * Repositions the entity toolbar on window scroll and resize.
     *
     * @param {jQuery.Event} event
     *   The scroll or resize event.
     */
    windowChangeHandler: function (event) {
      this.position();
    },

    /**
     * Determines the actions to take given a change of state.
     *
     * @param {Drupal.quickedit.FieldModel} model
     *   The `FieldModel` model.
     * @param {string} state
     *   The state of the associated field. One of
     *   {@link Drupal.quickedit.FieldModel.states}.
     */
    fieldStateChange: function (model, state) {
      switch (state) {
        case 'active':
          this.render();
          break;

        case 'invalid':
          this.render();
          break;
      }
    },

    /**
     * Uses the jQuery.ui.position() method to position the entity toolbar.
     *
     * @param {HTMLElement} [element]
     *   The element against which the entity toolbar is positioned.
     */
    position: function (element) {
      clearTimeout(this.timer);

      var that = this;
      // Vary the edge of the positioning according to the direction of language
      // in the document.
      var edge = (document.documentElement.dir === 'rtl') ? 'right' : 'left';
      // A time unit to wait until the entity toolbar is repositioned.
      var delay = 0;
      // Determines what check in the series of checks below should be
      // evaluated.
      var check = 0;
      // When positioned against an active field that has padding, we should
      // ignore that padding when positioning the toolbar, to not unnecessarily
      // move the toolbar horizontally, which feels annoying.
      var horizontalPadding = 0;
      var of;
      var activeField;
      var highlightedField;
      // There are several elements in the page that the entity toolbar might be
      // positioned against. They are considered below in a priority order.
      do {
        switch (check) {
          case 0:
            // Position against a specific element.
            of = element;
            break;

          case 1:
            // Position against a form container.
            activeField = Drupal.quickedit.app.model.get('activeField');
            of = activeField && activeField.editorView && activeField.editorView.$formContainer && activeField.editorView.$formContainer.find('.quickedit-form');
            break;

          case 2:
            // Position against an active field.
            of = activeField && activeField.editorView && activeField.editorView.getEditedElement();
            if (activeField && activeField.editorView && activeField.editorView.getQuickEditUISettings().padding) {
              horizontalPadding = 5;
            }
            break;

          case 3:
            // Position against a highlighted field.
            highlightedField = Drupal.quickedit.app.model.get('highlightedField');
            of = highlightedField && highlightedField.editorView && highlightedField.editorView.getEditedElement();
            delay = 250;
            break;

          default:
            var fieldModels = this.model.get('fields').models;
            var topMostPosition = 1000000;
            var topMostField = null;
            // Position against the topmost field.
            for (var i = 0; i < fieldModels.length; i++) {
              var pos = fieldModels[i].get('el').getBoundingClientRect().top;
              if (pos < topMostPosition) {
                topMostPosition = pos;
                topMostField = fieldModels[i];
              }
            }
            of = topMostField.get('el');
            delay = 50;
            break;
        }
        // Prepare to check the next possible element to position against.
        check++;
      } while (!of);

      /**
       * Refines the positioning algorithm of jquery.ui.position().
       *
       * Invoked as the 'using' callback of jquery.ui.position() in
       * positionToolbar().
       *
       * @param {*} view
       *   The view the positions will be calculated from.
       * @param {object} suggested
       *   A hash of top and left values for the position that should be set. It
       *   can be forwarded to .css() or .animate().
       * @param {object} info
       *   The position and dimensions of both the 'my' element and the 'of'
       *   elements, as well as calculations to their relative position. This
       *   object contains the following properties:
       * @param {object} info.element
       *   A hash that contains information about the HTML element that will be
       *   positioned. Also known as the 'my' element.
       * @param {object} info.target
       *   A hash that contains information about the HTML element that the
       *   'my' element will be positioned against. Also known as the 'of'
       *   element.
       */
      function refinePosition(view, suggested, info) {
        // Determine if the pointer should be on the top or bottom.
        var isBelow = suggested.top > info.target.top;
        info.element.element.toggleClass('quickedit-toolbar-pointer-top', isBelow);
        // Don't position the toolbar past the first or last editable field if
        // the entity is the target.
        if (view.$entity[0] === info.target.element[0]) {
          // Get the first or last field according to whether the toolbar is
          // above or below the entity.
          var $field = view.$entity.find('.quickedit-editable').eq((isBelow) ? -1 : 0);
          if ($field.length > 0) {
            suggested.top = (isBelow) ? ($field.offset().top + $field.outerHeight(true)) : $field.offset().top - info.element.element.outerHeight(true);
          }
        }
        // Don't let the toolbar go outside the fence.
        var fenceTop = view.$fence.offset().top;
        var fenceHeight = view.$fence.height();
        var toolbarHeight = info.element.element.outerHeight(true);
        if (suggested.top < fenceTop) {
          suggested.top = fenceTop;
        }
        else if ((suggested.top + toolbarHeight) > (fenceTop + fenceHeight)) {
          suggested.top = fenceTop + fenceHeight - toolbarHeight;
        }
        // Position the toolbar.
        info.element.element.css({
          left: Math.floor(suggested.left),
          top: Math.floor(suggested.top)
        });
      }

      /**
       * Calls the jquery.ui.position() method on the $el of this view.
       */
      function positionToolbar() {
        that.$el
          .position({
            my: edge + ' bottom',
            // Move the toolbar 1px towards the start edge of the 'of' element,
            // plus any horizontal padding that may have been added to the
            // element that is being added, to prevent unwanted horizontal
            // movement.
            at: edge + '+' + (1 + horizontalPadding) + ' top',
            of: of,
            collision: 'flipfit',
            using: refinePosition.bind(null, that),
            within: that.$fence
          })
          // Resize the toolbar to match the dimensions of the field, up to a
          // maximum width that is equal to 90% of the field's width.
          .css({
            'max-width': (document.documentElement.clientWidth < 450) ? document.documentElement.clientWidth : 450,
            // Set a minimum width of 240px for the entity toolbar, or the width
            // of the client if it is less than 240px, so that the toolbar
            // never folds up into a squashed and jumbled mess.
            'min-width': (document.documentElement.clientWidth < 240) ? document.documentElement.clientWidth : 240,
            'width': '100%'
          });
      }

      // Uses the jQuery.ui.position() method. Use a timeout to move the toolbar
      // only after the user has focused on an editable for 250ms. This prevents
      // the toolbar from jumping around the screen.
      this.timer = setTimeout(function () {
        // Render the position in the next execution cycle, so that animations
        // on the field have time to process. This is not strictly speaking, a
        // guarantee that all animations will be finished, but it's a simple
        // way to get better positioning without too much additional code.
        _.defer(positionToolbar);
      }, delay);
    },

    /**
     * Set the model state to 'saving' when the save button is clicked.
     *
     * @param {jQuery.Event} event
     *   The click event.
     */
    onClickSave: function (event) {
      event.stopPropagation();
      event.preventDefault();
      // Save the model.
      this.model.set('state', 'committing');
    },

    /**
     * Sets the model state to candidate when the cancel button is clicked.
     *
     * @param {jQuery.Event} event
     *   The click event.
     */
    onClickCancel: function (event) {
      event.preventDefault();
      this.model.set('state', 'deactivating');
    },

    /**
     * Clears the timeout that will eventually reposition the entity toolbar.
     *
     * Without this, it may reposition itself, away from the user's cursor!
     *
     * @param {jQuery.Event} event
     *   The mouse event.
     */
    onMouseenter: function (event) {
      clearTimeout(this.timer);
    },

    /**
     * Builds the entity toolbar HTML; attaches to DOM; sets starting position.
     *
     * @return {jQuery}
     *   The toolbar element.
     */
    buildToolbarEl: function () {
      var $toolbar = $(Drupal.theme('quickeditEntityToolbar', {
        id: 'quickedit-entity-toolbar'
      }));

      $toolbar
        .find('.quickedit-toolbar-entity')
        // Append the "ops" toolgroup into the toolbar.
        .prepend(Drupal.theme('quickeditToolgroup', {
          classes: ['ops'],
          buttons: [
            {
              label: Drupal.t('Save'),
              type: 'submit',
              classes: 'action-save quickedit-button icon',
              attributes: {
                'aria-hidden': true
              }
            },
            {
              label: Drupal.t('Close'),
              classes: 'action-cancel quickedit-button icon icon-close icon-only'
            }
          ]
        }));

      // Give the toolbar a sensible starting position so that it doesn't
      // animate on to the screen from a far off corner.
      $toolbar
        .css({
          left: this.$entity.offset().left,
          top: this.$entity.offset().top
        });

      return $toolbar;
    },

    /**
     * Returns the DOM element that fields will attach their toolbars to.
     *
     * @return {jQuery}
     *   The DOM element that fields will attach their toolbars to.
     */
    getToolbarRoot: function () {
      return this._fieldToolbarRoot;
    },

    /**
     * Generates a state-dependent label for the entity toolbar.
     */
    label: function () {
      // The entity label.
      var label = '';
      var entityLabel = this.model.get('label');

      // Label of an active field, if it exists.
      var activeField = Drupal.quickedit.app.model.get('activeField');
      var activeFieldLabel = activeField && activeField.get('metadata').label;
      // Label of a highlighted field, if it exists.
      var highlightedField = Drupal.quickedit.app.model.get('highlightedField');
      var highlightedFieldLabel = highlightedField && highlightedField.get('metadata').label;
      // The label is constructed in a priority order.
      if (activeFieldLabel) {
        label = Drupal.theme('quickeditEntityToolbarLabel', {
          entityLabel: entityLabel,
          fieldLabel: activeFieldLabel
        });
      }
      else if (highlightedFieldLabel) {
        label = Drupal.theme('quickeditEntityToolbarLabel', {
          entityLabel: entityLabel,
          fieldLabel: highlightedFieldLabel
        });
      }
      else {
        // @todo Add XSS regression test coverage in https://www.drupal.org/node/2547437
        label = Drupal.checkPlain(entityLabel);
      }

      this.$el
        .find('.quickedit-toolbar-label')
        .html(label);
    },

    /**
     * Adds classes to a toolgroup.
     *
     * @param {string} toolgroup
     *   A toolgroup name.
     * @param {string} classes
     *   A string of space-delimited class names that will be applied to the
     *   wrapping element of the toolbar group.
     */
    addClass: function (toolgroup, classes) {
      this._find(toolgroup).addClass(classes);
    },

    /**
     * Removes classes from a toolgroup.
     *
     * @param {string} toolgroup
     *   A toolgroup name.
     * @param {string} classes
     *   A string of space-delimited class names that will be removed from the
     *   wrapping element of the toolbar group.
     */
    removeClass: function (toolgroup, classes) {
      this._find(toolgroup).removeClass(classes);
    },

    /**
     * Finds a toolgroup.
     *
     * @param {string} toolgroup
     *   A toolgroup name.
     *
     * @return {jQuery}
     *   The toolgroup DOM element.
     */
    _find: function (toolgroup) {
      return this.$el.find('.quickedit-toolbar .quickedit-toolgroup.' + toolgroup);
    },

    /**
     * Shows a toolgroup.
     *
     * @param {string} toolgroup
     *   A toolgroup name.
     */
    show: function (toolgroup) {
      this.$el.removeClass('quickedit-animate-invisible');
    }

  });

})(jQuery, _, Backbone, Drupal, Drupal.debounce);
